When trees are to be removed from an area of land, often the most difficult part of the process is in dealing with the tree stump. Digging the tree stump out of the soil in which it is located is a time consuming and often unnecessary procedure. Digging destroys the natural meshing together of the soil created by the tree roots which has well known advantages such as in preventing soil erosion. Removal of the top portion of the stump is often all that is necessary. In general, removal to approximately six to twelve inches below the soil surface level is adequate for most purposes. For example, in road construction where the finished road level is four feet or greater above the existing level of topsoil, construction contracts allow the road to be built on top of the organic topsoil with tree stumps removed to existing ground level but leaving the roots intact below the existing ground level.
To remove the top portion of the stump several conventional devices have been produced in the past. Commonly the stump wood material is chipped or shredded with a disk or drum like wheel having wood cutting teeth on its cylindrical face or side surfaces. Such a toothed wheel has been, in previous cases, mounted to the end of a movable machine boom. The boom is moved to various positions in order to chip or shread away the wood material of the tree stump. The rotating wheel often digs into the adjacent topsoil creating a narrow trench or pit while eradicating the stump and roots to a depth of six to twelve inches. After the stump has been shredded or chipped, the wood material can be incorporated into the adjacent topsoil as organic material or may be removed to a separate composting site.
Examples of such conventional stump removing devices are described in U.S. Pat. Nos. 3,685,557 to Groce and to Bowling. The Groce and Bowling devices are mounted on a trailer which is towed behind a truck. Alternatively a dedicated tracked vehicle with a stump removing boom have been produced for use in a similar manner by Rayco Manufacturing Inc. of Wooster, Ohio, U.S.A. and sold under the trade marks RAYCO T115 and RAYCO T175 Hydrostatic Track-Drive Industrial Stump Cutter Forestry Mulcher/Mower.
In addition U.S. Pat. No. 3,389,726 to Good discloses a stump pulverizing apparatus which is hitched to the movable power bar of a conventional farm tractor. The Good apparatus has a platform supported on trailer wheels with an engine and fuel tank mounted to the platform driving an underhung toothed drum to pulverize tree stumps. The drum and platform are moved up and down rotating about the trailer wheel axle, by activating the hydraulic cylinder of the power bar of a convention farm tractor. The stump and adjacent topsoil are gouged out by the teeth of the drum to a depth of approximately twelve inches, whereas the remaining lower stump and root portions are left undisturbed since they do not interfere with normal farming operations.
In recent years, due to increasing consciousness regarding environmental impact of construction activities, constructions contracts are now calling for recycling or composting of tree stump material. For example, in the construction of new highways or building subdivisions, existing trees are cut down and the upper portions of the trees are shredded or chipped for composting or sold for fire wood. In the past it was considered acceptable to dig out stumps with earth moving machinery and burn the stumps on site. Due to air pollution concerns, burning is now considered to be an unacceptable form of disposal.
As an alternative to burning the stumps and other tree materials, it has in the past been considered acceptable to remove the stumps from the construction site and dump them in landfill or municipal garbage landfill sites. Again due to the recent trend in environmental consciousness, the cost of merely dumping stump materials in municipal waste dumps is becoming prohibitively high and in many cases dumps will not accept such wood materials. The rotting of the wood pollutes ground water supplies with humic acid, and as an ecological policy, municipalities refuse many materials which can be recycled or composted. Many municipalities now call for the shredding or chipping of all tree materials including stumps in order that they may be composted or used in grounds maintenance activities of the municipality.
Especially in new road construction, the call for chipping and shredding of numerous tree stumps in construction contracts is creating a demand for high capacity tree stump eradicating machinery. For example, when new roads are constructed through treed areas, the road builders must deal with numerous tree stumps.
The existing organic topsoil, in which trees are located, is generally stripped away and considered only suitable for topsoiling completed roadside areas such as ditches or slopes covered with grass or other vegetation. However, where the finished elevation of the road is four feet or greater above the level of existing organic topsoil, the topsoil need not be removed but may be covered with the compacted earth fill which would build up the roadbase. In such a case, it is only necessary to remove the top portion of the stumps to the level of the topsoil during road construction and to incorporate the chipped stump material into the adjacent organic topsoil.
The conventional devices described above are generally inadequate for roadbuilding applications since commercially available devices are of small size and low capacity designed to remove the odd stump encountered in farming activities and maintenance of parks or other urban areas.
To answer the need for high capacity stump removal devices stump grinding wheels have been conventionally mounted to the boom of a large backhoe excavator. U.S. Pat. Nos. 4,041,996 and 4,180,107 to Grover show a conventional backhoe excavator with a toothed grinding drum mounted to the end of the excavator boom.
The advantage of this type of device is that the backhoe excavator or other earth moving machinery often have tracks or large rubber tires which enable them to traverse over rough terrain encountered in construction activities. The relatively large boom size of a backhoe enables a backhoe operator to remove tree stumps within a large radius of the machine's position without requiring the machine itself to be constantly relocated.
In the above Grover patents the device described is attached to the boom of the backhoe with removable pivot pins. Backhoe booms are conventionally provided with removable pivot pins to quickly attach and detach various implements for construction activities. For example, differently sized or shaped excavator buckets, and pneumatic hammers are commonly connected and easily removed from the excavator boom in this manner. The boom of a backhoe also includes a hydraulic cylinder attached to a linkage mechanism in order to manipulate the implements attached to the end of the boom.
The Grover device however suffers from significant disadvantages and has not been commonly adopted. To minimize the weight and size of the Grover device, the toothed drum is driven by hydraulic motors. The hydraulic motors are attached by hydraulic hoses to the hydraulic system of the backhoe excavator, which is powered by the diesel engine of the backhoe. In such a manner the operator has full control over the operation of the boom and the operation of the toothed wheel from the cab of the backhoe. Hydraulic motors however are very prone to stalling under high load and the practical power which can be delivered to the rotating drum by the backhoe hydraulic system is inadequate to perform the stump grinding operation. Stumps from hardwood trees, or stumps which have grown around rocks require the rotating drum to exert extremely high forces which the applicant has found in practice cannot be delivered by the Grover type of device commercially available.
A further serious disadvantage of conventional stump removing devices including the Grover device is in respect of the vibration, light weight of the stump remover, and kick back of the boom encountered in operation. Such a stump removing device is limited to the power output of the backhoe, since the Grover type stumping device depends on the backhoe hydraulic system for power.
The booms of conventional stump grinding devices are essentially cantilevered structures which are raised and lowered independent of the ground surface upon which the machine or trailer rests. Such cantilevered booms are raised and lowered, and apply downward force during grinding with hydraulic cylinders.
In the case of the Grover apparatus, the boom of a backhoe excavator extends a significant distance from the center of gravity of the machine. When the rotating wheel or drum of the device is engaged with a tree stump, significant vibration occurs due to the cantilevering of the boom, light weight and the relatively slender construction of conventional booms. In particular when stones or other serious obstacles are encountered, the rotating wheel may kick back or lift the boom and attached machinery.
Vibration and kick back therefore represent serious draw backs in the efficient removal of stumps and present significant opportunities for wear and damage to the machinery. Due to these disadvantages the speed at which stumps are removed is seriously limited.
Although the Grover type device attached to the end of a backhoe is considered advantageous in construction activities, the Grover device suffers from the disadvantage that it is required to be connected and disconnected from the backhoe hydraulic system. The connection of hydraulic hoses to the backhoe reduces the size and weight of the stump removing apparatus however it introduces a serious disadvantage in the speed and ease with which the device may be installed and removed from a backhoe.
A common backhoe excavating bucket is removed and installed by merely removing two pivot pins. The Grover device requires the removal of such pins but in addition requires a mechanic to safely disconnect and reconnect high pressure hydraulic hoses. The operator of a backhoe is generally competent to safely remove and reinstall the pivot pins however a significant danger and increased level of skill accompanies the connection and disconnection of high pressure hydraulic hoses. From a practical point of view the backhoe operator must standby while a mechanic disconnects and reconnects the high pressure hydraulic hoses.
In order to maximize the use of the backhoe it may be necessary to disconnect and reconnect the stump grinder numerous times and preferably as quickly as possible. Therefore the requirement of the Grover apparatus to connect and disconnect hydraulic hoses represents a serious limitation on the practical use of such a stump removing device.
Conventional devices also suffer from the disadvantage that the stump shredding or chipping wheels during operation spew soil and wood particles randomly over the work site. The view of the machine operator may be seriously obscured. In addition, flying particles of wood, soil or gravel may create serious safety problems. Conventional devices often include a partial fender or guard over a portion of their circumference to protect the operator. However, due the need to closely observe the progress of the wheel through the stump material it is not practical to completely eliminate the spewing of wood and soil particles in using conventional devices.
It is desirable to produce a stump shredding or chipping device which is capable of the heavy duty demands of road building and other construction activities which can be easily and simply connected and re-connected to various earth moving machines such as a backhoe excavator.
It is also desirable to produce a stump removing device which does not suffer from the problems of vibration and kick back presented by conventional devices which are attached to the end of an unsupported cantilevered boom, and which are limited to the hydraulic power output of a conventional backhoe.
Further it is desirable to contain the spewing of wood and soil particles by the stump removing operation for the safety of the operator and persons working in adjacent areas.